Does Shotspotter Help Cops Keep Us Safe?

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Last week I had an experience that was weirdly scary not in the moment I was in danger but hours later when I realized I had been in danger. I was in a car on the highway in the late afternoon when I got an alert on my phone that said ShotSpotter had just detected more than a dozen gunshots near my location. “ShotSpotter” is a surveillance system that covers a particular city in sensors, allowing it to detect and triangulate the location of loud noises, like fireworks, helicopters, or the thing it’s designed to detect: gunshots. Apps like “Citizen” relay ShotSpotter alerts to users.

A few minutes after I got the alert, I saw cop after cop after cop racing down the highway in the opposite direction. I opened the app and it showed that the shots were detected in a neighborhood we were passing by off the highway and didn’t think anything more of it.

But three or four hours later, I was traveling back home and saw that the other highway lanes were closed right where I had received the alert. I checked Citizen and saw that it hadn’t been an incident in a neighborhood: it was a freeway shooting, in which someone leaned out of their car window with two guns and unloaded a hail of bullets into a car in the other lane, and it happened literally right behind us.

Bonkers, right? Who knew I could get even MORE anti-gun than I already am?

But this incident got me thinking: what on Earth did I gain by having that app on my phone? It didn’t make me any safer. All it did was freak me out long after the incident was over. I installed it because I was curious about what’s happening around me, but does it really make me more informed? Or does it just make me more scared of my neighbors?

And there’s an extra facet that has been in the back of my mind for awhile now: does technology like ShotSpotter really make any of us safer?

At first blush it sounds like a good idea, at least in a country like the United States where on average someone dies of a gunshot wound about every ten minutes: if someone is shot in an otherwise deserted area and left for dead, ShotSpotter could immediately alert emergency services to save their life. No need to wait for bystanders to call 911 and give their location when there’s an active shooter situation: ShotSpotter hears it and tells the cops exactly where to go.

But does it really work like that in practice? Well!

According to Shotspotter, they’re currently set up in 120 cities around the US, plus one in South Africa, and have been operating for about 25 years. They set up audio sensors generally in “high crime” neighborhoods, and those microphones are always on; when they pick up a loud noise, two algorithms determine the location and whether it was a gunshot. If it’s considered a gunshot, within 60 seconds a human reviewer confirms the audio and sends out the alert to police (and apps that use the tech).

Now, the first thing that might pop into your head, especially if you’re a paranoid weirdo like me, is “hold on, there are microphones everywhere that are always listening? Isn’t that a big dodgy in the ol’ privacy sense?” And you would be correct! It IS dodgy. In 2012, police in New Bedford, Massachusetts used ShotSpotter audio recordings of an argument between two people on the street to bolster a murder charge against them. ShotSpotter’s spokesperson insisted that that was very strange because “It’s an acoustic sensor. It’s not a microphone, and it’s only activated when a loud boom or bang happens,” said Barrett, who added: “It’s not listening. There is no listening.” Did you get that? NO LISTENING. Except…except in the case of that one argument. So if you don’t want to be listened to just be very quiet, okay? And don’t murder anyone. Or be suspected of murdering anyone. Or of anything else illegal.

The next thing you may wonder is, how often does this technology actually correctly identify a gunshot along with its precise location? Shotspotter claims to have a 97% accuracy rate, independently verified by Edgworth Analytics. But that stands in stark contrast to what they said back in 2017, when their own forensic analyst Paul Greene testified in a murder trial in San Francisco about the 80% accuracy they guaranteed to cities back then:

“Our guarantee was put together by our sales and marketing department, not our engineers,” Greene said.

“We need to give them [customers] a number,” Greene continued. “We have to tell them something. … It’s not perfect. The dot on the map is simply a starting point.”

ShotSpotter’s CEO, Ralph Clarke, admitted “The 80 percent is basically our subscription warranty, as you will. That doesn’t really indicate what someone will experience,” he said, adding that it is usually far better.

Shotspotter’s present day 97% statistic is based on their own data. In its independent analysis, Edgeworth Analytics notes “However, information on potential errors relies on clients reporting those potential errors to ShotSpotter.” So apparently, cities only tell the company an alert was in error 3% of the time.

But the MacArthur Justice Center at Northwestern Pritzker School of Law thinks the number of errors is far higher. Instead of looking at ShotSpotter’s in-house data, they examined 21 months of ShotSpotter data recorded by the city of Chicago, finding that “89% (of police deployments) turned up no gun-related crime and 86% led to no report of any crime at all. In less than two years, there were more than 40,000 dead-end ShotSpotter deployments.”

That report was later backed up by the Chicago Inspector General, who “concluded from its analysis that CPD responses to ShotSpotter alerts rarely produce documented evidence of a gun-related crime, investigatory stop, or recovery of a firearm. Additionally, OIG identified evidence that the introduction of ShotSpotter technology in Chicago has changed the way some CPD members perceive and interact with individuals present in areas where ShotSpotter alerts are frequent.”

That last bit is particularly relevant to Chicago, considering that that’s where police responded to a ShotSpotter alert by shooting and killing 13-year old Adam Toledo, shortly after the boy had dropped the gun he was holding and raised his empty hands in the air. That’s the kind of incident that fuels opponents’ accusations that ShotSpotter keys up cops to go into situations more aggressively than they otherwise might (a criticism that ShotSpotter dismisses out of hand, writing on their website “there is no evidence supporting the claim that ShotSpotter alerts result in police arriving on scene “hyped up” potentially creating dangerous situations.”)

The questions of accuracy, wasting police resources on dead-end deployments, and encouraging aggressive police responses are bad enough, but opponents have also accused ShotSpotter of manipulating data to fit police narratives after the fact. In Rochester, New York, which has ShotSpotter, officer Joseph Ferrigno shot Silvon Simmons three times in the back in 2017. Ferrigno claimed Simmons had shot once at him first, while Simmons claimed he did not. According to an in-depth report on the incident by Reuters:

“Initially, according to company records and trial testimony reviewed by Reuters, ShotSpotter told Rochester police that it identified the sounds that night as coming from a helicopter, not a gun. Then, after Rochester police told ShotSpotter the department was investigating an officer-involved shooting, the contractor reclassified the sounds as three gunshots, “per the customer’s instruction.” After another communique from Rochester police, ShotSpotter analyzed its logs again. This time, ShotSpotter concluded that its sensors picked up four gunshots, all near Simmons’ house.

“Ferrigno had himself fired four times, which fit the updated ShotSpotter analysis. But what of the shot that Ferrigno insisted Simmons fired?

“Rochester police requested another audio analysis from the contractor, court records show. The ShotSpotter report was revised once more. This time, a customer support engineer testified, sensors identified five shots – a finding that now conformed with Ferrigno’s version of events.

“Simmons’ defense team had sought the original recordings and other ShotSpotter records. But the company “refused to honor the defense subpoena,” Riley disclosed in a motion. If the defense wanted the information, it would have to pay more than $10,000, court records show, “a cost that was well outside the budget of the Monroe County Public Defender’s Office.””

Now, I normally don’t quote so extensively from any one source, but I have to be very careful here. ShotSpotter has been accused several times of manipulating data at the request of police departments, and they are very quick to say that that is a lie. In fact, they have managed to get complicated corrections from outlets like the Associated Press and are currently suing Vice News for defamation.

Friends, I am but a humble YouTube science enthusiast, so I will merely report the facts as I understand them.

Alongside all this controversy is the fact that ShotSpotter costs cities hundreds of thousands of dollars a year or more, with cities like Chicago paying about $10 million a year. So it’s no surprise that some cities, like Charlotte, North Carolina, have canceled the service, and others are fiercely debating whether to give it a go. That’s the case in Durham, North Carolina right now, where the city council is debating whether to spend $200,000 on ShotSpotter. Opponents say that there are better ways to control crime in the city, but the city’s mayor “says these reforms and ShotSpotter are not mutually exclusive: “I think the people reject the zero-sum game. It’s not either/or.”” But…it literally is, that’s how money works. If you spend it on one thing you can’t spend it on another thing, too. You can spend $200,000 on a system that may waste police officers’ time in 86% of cases, or you can spend that same $200,000 on gun control, police deescalation training, a living wage, prison reform, housing guarantees, education, school lunches, libraries, after school programs, or other scientifically proven ways to reduce violent crime.

And honestly, that’s why I’m personally not a fan of my city having this service. It IS a zero-sum game, and the losers of the game are innocent people being hassled by cops without cause, people living in cities with no money left over for social services, and cops that might want to make a positive difference in their neighborhoods instead of chasing after dead-ends all day and night. The only winners, in my opinion, seem to be ShotSpotter shareholders.

Rebecca Watson

Rebecca is a writer, speaker, YouTube personality, and unrepentant science nerd. In addition to founding and continuing to run Skepchick, she hosts Quiz-o-Tron, a monthly science-themed quiz show and podcast that pits comedians against nerds. There is an asteroid named in her honor. Twitter @rebeccawatson Mastodon Instagram @actuallyrebeccawatson TikTok @actuallyrebeccawatson YouTube @rebeccawatson BlueSky

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